Portion of a toothbrush handle



FIG. 1 is a perspective view of the embodiment of a portion of a toothbrush handle, showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a left-side view thereof;

FIG. 5 is a right-side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines showing a brush head and the remainder of the handle illustrate environmental structure and portions of the toothbrush handle that form no part of the claimed design. 

The ornamental design for a portion of a toothbrush handle, as shown and described. 